Throttle bodies, cold air intakes and headers

[brkntrxn]

The "kink" (ie T10) is still there in the new configuration at CMP (full course). Only T12, T13, and T14 have been changed, along with repaving in some of the other key turns around the track.

Here are some of my thoughts (some are echoes of those above):

- As for your 97 and any modular 4.6 car with low torque, weight reduction is the key. Consider swapping the k-member, deleting AC, lightweight wheels and body parts, etc.

- An aftermarket throttle body on a naturally aspirated 4.6 does not provide any gains. Unlike the 302s, the stock 4.6 TB is good for over 600hp in most applications, so I wouldn't bother with that upgrade.

- Cold air intake such as JLT

- Ported and polished heads and intake are good proven ways to get gains.

- Headers. Longtubes are better, but you may have issues with dropping the trans later. If someone makes them, look into mid-lengths for your car. I have JBA shorties on my car and I like them, but they are leftover from the blower setup where longtubes are not as important.

- A set of aftermarket (properly degreed) cams, but that can get expensive because you are tearing into the motor

- A bump in compression and a .020 overbore are also good if you happen to go that far (so is stroking it but that is another can of worms)

- Don't forget suspension. More ground is made up in turns and in braking zones that on the straights.


Kevin


(edit: added longtubes comment)

[puzzle13]

Originally Posted by Tnmustcobra

I was looking at the NASA mid-Atlantic schedule and they have dates with VIR full course on 2-21/22-09 weekend and then again on 3-28/29-09 weekend. I was thinking the March weekend would be a little warmer weather and the last time I went to VIR in February it rained. The NASA Southeast schedule shows CMP on 2-6/7-09 weekend, then Road Atlanta on 3-14/15-09 weekend and then back to CMP on 5-2/3-09 weekend. I really like VIR and RA as they are my favorite tracks. I have not been to CMP since it was reconfigured and I bet it is really fast now. I guess the "Kink" is gone....I really liked that feature! I just looked up the CMP schedule with the Cobra Club March 14/15 weekend and that is tempting, too! I also noticed Burke was running Tech and Scott Whitehead was classroom instructor. Would be good to see what Burke has done to his Cobra and maybe run in the same group. I also could say hi to Scott....we "bumped" into each other at Nashville Superspeedway a few years ago. Scott is really a cool dude and he helped me with my set up on the race car. Last time I came to CMP and ran with the Cobra Club...back in 2006 or 2007...I think... I helped instruct and might try that again if there are any openings for instructors. All these dates are so close together it will be hard to make a decision.

David Morrison

1997 Mustang Cobra
1987 Porsche 944 (NA)
2004 Ford F-350 Dually
1988 Mustang AV8SS race car (sold)

You should run VIR on Feb. 7 & 8 with Vernon and myself at the Tarheel event. We always seem to get good weather at that event ... knock on wood! The kink is still there at CMP and imho it really isn't any faster or better, just different. I think Vernon, Burke & I are going to run RA with MVP Track Time in November. I have heard too many negative things about HPDE's with NASA. We are trying to maximize track time per event now. We will be looking at the schedule during our bowling event in G'boro on January 10th. Burke got his engine running tonight and now we will be putting the finishing touches on reassembly & bodywork over the next few days. I should be getting my 03 back from paint on the 5th. Burke is waiting for an email if you want to discuss mods!

[Tnmustcobra]

I just looked at the track map for CMP and notice the changes made and that the kink is still there. I just thought I had heard mention that the "kink" had been modified. I think the changes are good and will make a nice continuos turn going thru 12 and 13. Turn 14 looks to be wider and I am sure the racing series will appreciate the wider track and greater radius to get around 14 and have a little more room to make the pass. As far as NASA....What I like about this asssociation is having the HPDE, TT and race groups on the same weekend. If someone wants to eventually race in a series, they provide a variety of classes to choose from and you can talk to the racers and get their input on cost and effort. Track time may be less...I think they usually had 4 sessions per day at 25 minute sessions...but the classroom instructors and in car instructors were usually very informative and thorough on the physics and techniques for driving fast on a track. I learned a lot from Dan Unkefer and when I had advanced beyond the HPDE classes, I would still ask him questions on certain areas of the tracks that I was driving and where I felt I needed to pick up speed and he was always willing to share his time to help when asked. You could also ask different drivers what they were doing as there are different driving styles and cars handle differently, so you may find the answer that best fit your style and car's handling characteristics. I know that if you want to race Mustangs, then NASA has 3 classes to choose from; CMC, AI , and AIX. Each of these classes have different levels of cost to go racing and the classes are pretty competitive. I also raced in the AV8SS series and that was similar to the AI/AIX series, but covered a greater geographical area of tracks verses the closer track selection of the NASA regional groups. I never raced in the SCCA (just autocrossed in the local region here in East Tennessee). I attended open track at Road Atlanta with the Panoz group a couple of years ago and I enjoyed the fact that I could let a passenger ride with me....my brother would ride with me and we had a blast! They just required the same waivers and equipment as the driver in order to ride. I don't think they do that anymore as I have seen some accidents on track with passengers and I think the risk was too great to let drivers with limited experience take out passengers as they had a tendency to over drive the track ...probably trying to show-off. I was running in a TT at a Hyper-fest at Beaver Run in 2003 and they were letting spectators ride with us during a special session and the spectators were able to experience what it was like to be in a car on track at speed.

Back to the original topic. I have e-mailed Burke and gave him some info and will await for his response. I think the heads and cams ....possibly a stroker kit would be what I would want to do, but will probably prepare some planning before going into the engine and will wait until after the 2009 season ends to allow proper time to possibly go in this direction. For now....just try to set up the MM suspension for the track and improve my skills with the car as is...maybe try to shed some weight here and there throughout the next few months.

Thanks to all. Sorry for being so long winded! I can't help it ...I like fast cars and driving fast and that is my passion!

David Morrison

1997 Mustang Cobra
1987 Porsche 944 NA
2004 Ford F-350 Dually
1988 Mustang AV8SS Unlimited race car(sold)

[brkntrxn]

Originally Posted by puzzle13

You should run VIR on Feb. 7 & 8 with Vernon and myself at the Tarheel event. We always seem to get good weather at that event ... knock on wood! The kink is still there at CMP and imho it really isn't any faster or better, just different. I think Vernon, Burke & I are going to run RA with MVP Track Time in November. I have heard too many negative things about HPDE's with NASA. We are trying to maximize track time per event now. We will be looking at the schedule during our bowling event in G'boro on January 10th. Burke got his engine running tonight and now we will be putting the finishing touches on reassembly & bodywork over the next few days. I should be getting my 03 back from paint on the 5th. Burke is waiting for an email if you want to discuss mods!

I think someone has been looking at my spreadsheet.....


Kevin

[tcrews]

Originally Posted by cobrabitn

You have to see where you max out in 4th gear when you are running at VIR. My 5.0L is maxing out at 120 mph and when I hit 5th, it just dies. Having 4.10's is good for the street but if you are maxing out at VIR and still have asphalt left then you should go to a higher or even stock 3.27's. You don't want to waste the power you have by holding steady. JMHO

I was going to say that Mike about Burke but I didn't want to put his e-mail addy out there with all of the spam bots we have visiting our forums every day.

Tony, a stock 4.6 Cobra (96-98) can pull 160 mph in 4th gear with 4.10s.....at 7,000rpm. With stock gears your top speed is going to be in the low 150's. Some of the cross country racers have shown videos of their cars pulling 160 mph in 4th (something they said they couldn't do with 3.27).

Now Tnmustcobra, throttle bodys on these cars do nothing except remove money from your wallet. Unless you add major major supercharged boost...you should stick with the stock one.

Your "basic" power adders that work will be:

Underdrive pulleys
Headers (longtubes will make more usable torque in the powerband)
Offroad X or H (specific to going longtube or stock/shorties)
Cold Air Induction (not much...but will help)

Your "advanced" power adders that work will be:

Ported/Polished heads
Cams (specific to your needs and modified/stock heads)
FR500 Heads/Cams and Intake
Big Bore or Stroker engine...though if you plan on long term high rpm, the Big Bore is a much better choice for you. The 4.6 has a relatively long stroke for such a small engine....making it longer and having such a high revving nature is not something I'm fond of.
Higher compression (if staying naturally aspirated).

If you've got the desire and money I'd suggest the following:

Ported/polished stock heads and intake
Big Bore 5.0(money) or a .030 overbore (cheaper) with Forged pistons/rods with a bump in compression to at least 10.5:1, probably even 11.5:1
BBK Longtube headers, offroad X/H pipe
CAI of your choice
4.10 gears

Have the build discussed with your "builder" to maximize the air flow/velocity for your intended use, primarily in head/intake porting and cam choices. These engines love to stay in the upper rpms and having good flowing engine will really move the car, but too much "early" air flow (low air velocity) can kill your torque coming out of a turn unless you can hit a good RPM to keep the air moving (this is where the 4.10s, bump in compression help...4.10s for rpm, compression for torque).

of course reducing weight is like adding free horsepower so anything you can do there will help.

[brkntrxn]

Originally Posted by tcrews

Tony, a stock 4.6 Cobra (96-98) can pull 160 mph in 4th gear with 4.10s.....at 7,000rpm. With stock gears your top speed is going to be in the low 150's. Some of the cross country racers have shown videos of their cars pulling 160 mph in 4th (something they said they couldn't do with 3.27).

Tom,

I disagree with that statement. From running the calculators and from real life experience, a Cobra in 4th gear (1:1) with 4.10s and 25-26" tires, it will max out in the mid 120-130 (depending on rpm). My 99 Cobra was setup in that exact manner (26" tire, 275/40/17), 4.10 and at 6600 rpm redline going through the traps (or at the straights on VIR) it was hitting 124 in 4th gear.

Specifically, in 4th gear (1:1 ratio), 26" tire, 7000 rpms, 4.10 gear = 132.06 mph. 5th gear in that setup will take you to 197mph if you can get past aero issues.

4th gear, 26" tire, 7000 rpms, 3.55 gear = 152.52. 5th gear will take you to 227mph if you can get past aero issues.


Kevin

[tcrews]

The biggest problem, beside aero-dynamics, with calculating out is that those calculations are based on unlimited horsepower.

I may be off on what I was remembering....I just recall some of the cross-country racers discussing the merits of gear changes, etc... It might have been that a stock Cobra will stop pulling in 4th gear before redline and will not pull at all in 5th while a 4.10 geared Cobra will pull 4th to redline and still pull some in 5th.

So I must have been wrong on the gear (4th vs. 5th) but I distinctly remember the discussion and the associated pictures they posted of their Cobra's speedometer. I have the picture "somewhere" and I'll see if I can find it (3 computers, 1 laptop, 4 TB of storage....it might be a while).

I just remember the discussion involving weight, aero, resistance and the engines ability to pull/push the car beyond certain rpms (.....as torque and horsepower deminished the rpms would hold before maxing out)

Basic calc show:

160 mph - 3.27 - 4th gear - 6,848 rpm
160 mph - 4.10 - 5th gear - 5,752 rpm

I doubt any would use 5th in road-racing.....but these cars do prefer rpm (to a point of decreasing HP/TQ) and 3.27's sure don't help them.

[brkntrxn]

Originally Posted by tcrews

The biggest problem, beside aero-dynamics, with calculating out is that those calculations are based on unlimited horsepower.

I may be off on what I was remembering....I just recall some of the cross-country racers discussing the merits of gear changes, etc... It might have been that a stock Cobra will stop pulling in 4th gear before redline and will not pull at all in 5th while a 4.10 geared Cobra will pull 4th to redline and still pull some in 5th.

So I must have been wrong on the gear (4th vs. 5th) but I distinctly remember the discussion and the associated pictures they posted of their Cobra's speedometer. I have the picture "somewhere" and I'll see if I can find it (3 computers, 1 laptop, 4 TB of storage....it might be a while).

I just remember the discussion involving weight, aero, resistance and the engines ability to pull/push the car beyond certain rpms (.....as torque and horsepower deminished the rpms would hold before maxing out)

Basic calc show:

160 mph - 3.27 - 4th gear - 6,848 rpm
160 mph - 4.10 - 5th gear - 5,752 rpm

I doubt any would use 5th in road-racing.....but these cars do prefer rpm (to a point of decreasing HP/TQ) and 3.27's sure don't help them.

I agree. And the upper 5th gear potential is only a theoretical based on unlimited horsepower and no regard to aero issues.

People do use 5th in road racing. Anyone with a 4.10 gear or lower (numerically higher) will need 5th on long straights such as VIR full course back stretch (and maybe the front stretch), Roebling Road front, Road Atlanta back stretch, etc. to continue accelerating... rather than running it up to redline and holding it there while getting passed by someone willing to upshift to 5th.


Kevin

[Tnmustcobra]

I have ran my 97' Cobra at VIR in stock trim with the 3:27 gears and then later made about 40 rwhp gain and swapped to a 3:73 gear. Had R compounds later as well. With that set up I still had no need to shift to 5th since I only ran 4th up to about 6800 rpm on the back straight. I do know that when I was running a conservative lap and short shifted into 5th, the car still pulled a little....but that was at about 125 mph or so. Not sure what speed I was running because my speedo has not been corrected since the 3:73 gears were installed. Now that I have all new MM suspension parts and some more experience from the AIX and AV8SS Unlimited racing series, I feel I will be coming off the corners with a little more speed. I had wondered what the math was for going to 4th gear with 4:10 gears...which looks to be about
130mph-135mph maximum. I know all the Road and Track articles for the 97' Cobra also stated top end was about 156 as tested and was in 4th...the car slowed down when they shifted to 5th. The aero issues are the big problem for 5th gear. That was part of the reason for the original question for HP gains as I thought if I could get above 400 rwhp, then I could stay in 4th most of the time except on really long straights and then I could pull 5th better if needed with the 3:73 gears. I know that by swapping to 4:10 gears, I would accelerate off the corners better and should be able to shift in 5th if needed and still pull decent until I reach the latest braking zone. Of course, now that I see how difficult and costly it is to get 400rwhp from the 97' Cobra, I still don't have a clear picture what I want to do. I would have preferred to keep 3:73 and not have to use 5th, but 4:10's would be cost effective for better acceleration. I have made some weight savings as that is one direction to go in lieu of spending money to make more hp. 20 pounds here...20 pounds there...not much, but every little bit of weight loss helps. Let's see...how about if I lose about 20 pounds as well!

David Morrison

1997 Mustang Cobra
1987 Porsche 944 NA
2004 Ford F-350 Dually
1988 Mustang AV8SS Unlimited race car (sold)

[brkntrxn]

On my 99, when I had the supercharged 554rwhp and 4.10s setup, I absolutely had to shift to 5th because I was hitting 140+ on the back stretch of VIR. With 4th winding out at 124 with my 6600 shift pill in the shift light, I had to go to 5th to continue accelerating up to 140-145 by the time I got to the beginning of the braking zone.

Fast forward to late last year, I now have naturally aspirated 324rwhp (mustang dyno, more on a dynojet) and 3.55s, I stay in 4th since I don't have the power nor the gear to wind out 4th to 6800rpms before hitting the same braking zone on the back stretch of VIR.

Just my .02 on my experiences.....

I say go with the 4.10 if you want and go for weight reduction.

[snakbitn]

I have a 98 cobra with 310 rwh 302 tq with 373 gears and I hit 135mph @ 6800 redline in forth gear. And at all the long tracks I go to 5th it still pulls alittle up to around 145mph at like vir or road atlanta but that is all it will do which is pretty damn quick but the car weight is 3100 lbs plus my big a--.

[cobrabitn]

I basically have problems pulling in 5th gear with 302 rwhp and 333 ft lbs of torque in my 5.0 Cobra.

Thanks for clearing that up brkntrxn as I thought the number Tom gave was a tad high. Personally, you have other options like gear changing in the transmission like going to .85 instead of the .68 to one. That will allow you to run fifth gear on the front stretch at VIR and still be pulling all the way to turn one. Remember, I run a 5.0 so 4.10 gears would be out for me as I couldn't take it but I probably would be able to use 5th more if I did go to that gear. I might be going there too much though...

Oh, to stay on topic, the throttle body would be a waste of money just like Tom said!

[Cobra99.kr]

A good source guide for high performance Mustang is a book authored by Sean Hyland, High-Performance Mustang Builder's Guide 1994-2004 put out by CarTech (www.cartechbooks.com).
They also put out How to Build Max Performance 4.6 Liter Ford Engines.